Synthesis and characterization of a Ni nanoparticle stabilized on Ionic liquid-functionalized magnetic Silica nanoparticles for tandem oxidative reaction of primary alcohols

Article abstract of DOI:10.1002/aoc.4452

In this research, preparation of the magnetic nanoparticle, coating by a silica shell using (3-aminopropyl) triethoxysilane and synthesis of a novel sulfonic acid-substituted imidazolium-based ionic liquid onto the surface of these particles via a multi-component reaction, is described. The functionalized nanoparticles was loaded by Ni nanoparticles and characterized by means of techniques such as XRD, FTIR, SEM, EDX, TEM, TGA and ICP-OES. The nanostructures have spherical shapes that ranged in size from 80 to 100?nm. The catalytic activity of these nanoparticles was tested in aerobic oxidation of primary alcohols that showed good performance in the wide range of primary alcohols in water at mild reaction conditions. As a second step of this work, the tandem oxidative synthesis of alkylacrylonitriles and bisindolylmethanes were investigated using primary alcohols under oxidation conditions. This catalyst system can be recovered using external magnet and reused for five consecutive cycles without significantly less of its activity.

Full text of DOI:10.1002/aoc.4452

Received: 4 March 2018
DOI: 10.1002/aoc.4452
Revised: 7 May 2018
Accepted: 13 May 2018
F U L L P A P E R
Synthesis and characterization of a Ni nanoparticle
stabilized on Ionic liquid‐functionalized magnetic Silica
nanoparticles for tandem oxidative reaction of primary
alcohols
1
2
3
4
Rahim Hosseinzadeh‐Khanmiri
| Yaser Kamel | Zahra Keshvari | Ahmad Mobaraki |
5
1
5
Gholam Hossein Shahverdizadeh | Esmail Vessally | Mirzaagha Babazadeh
1
Department of Chemistry, Payame Noor
In this research, preparation of the magnetic nanoparticle, coating by a silica
shell using (3‐aminopropyl) triethoxysilane and synthesis of a novel sulfonic
acid‐substituted imidazolium‐based ionic liquid onto the surface of these parti-
cles via a multi‐component reaction, is described. The functionalized nanopar-
ticles was loaded by Ni nanoparticles and characterized by means of techniques
such as XRD, FTIR, SEM, EDX, TEM, TGA and ICP‐OES. The nanostructures
have spherical shapes that ranged in size from 80 to 100 nm. The catalytic
activity of these nanoparticles was tested in aerobic oxidation of primary alco-
hols that showed good performance in the wide range of primary alcohols in
water at mild reaction conditions. As a second step of this work, the tandem
oxidative synthesis of alkylacrylonitriles and bisindolylmethanes were investi-
gated using primary alcohols under oxidation conditions. This catalyst system
can be recovered using external magnet and reused for five consecutive cycles
without significantly less of its activity.
University, Tehran, Iran
2
Department of Chemistry, Payam Noor
University, Sari, Iran
3
Department of Science, Lorestan
University, Lorestan, Iran
4
Department of Analytical Chemistry,
Faculty of Chemistry, University of
Kashan, Kashan, Iran
5
Department of Chemistry, Tabriz
Branch, Islamic Azad University, Tabriz,
Iran
Correspondence
Rahim Hosseinzadeh‐Khanmiri,
Department of Chemistry, Payame Noor
University, Tehran, Iran.
Email: hosseinzade.rahim@yahoo.com
Highlight
•
Synthesis a novel functionalized magnetic silica nanoparticles
Multi‐component functionalization of the nanoparticles surfaces
Synthesis a sulfonated imidazolium‐based ionic liquid
Oxidation of primary alcohols
•
•
•
KEYWORDS
Aerobic oxidation, Ionic liquid, Multi‐component surface functionalization, Primary alcohol, Silica
nanoparticles
1
| INTRODUCTION
surface area, no toxicity, chemical and thermal stability,
ease of modification and functionalization, and magnetic
[
1]
Magnetic silica nanoparticles (NPs) have been widely
studied as a catalyst in organic transformations owing to
several interesting properties of these NPs such as high
recyclability. The magnetic silica NPs can be modified
[2]
through a sol–gel process using organosilanes. The
modified NPs are potentially advantageous for organic
Appl Organometal Chem. 2018;e4452.
wileyonlinelibrary.com/journal/aoc
© 2018 John Wiley & Sons, Ltd.
1 of 9
https://doi.org/10.1002/aoc.4452

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HOSSEINZADEH‐KHANMIRI ET AL.
[
3]
functionalization by reaction with active species. The
chemically organic functionalization of these inorganic
NPs can be significantly improved their dispersion prop-
erties in organic or aqueous mediums and increased the
ability of NPs surface to interact with reagents in organic
reactions using π‐π interaction, hydrogen bonding and
dipole–dipole interaction between the organic function
surfaces as a catalyst system for aerobic oxidation of pri-
mary alcohols (Scheme 1).
2
| EXPERIMENTAL
.1 | General
2
[4]
of surface and substrates. In recent decades, many
types of modified and functionalized magnetic silica (or
Silica) NPs have been reported as catalyst in organic
Aminopropyltriethoxysilane (APTES, 99%) and all mate-
rial and solvent were purchased from Merck and Aldrich
companies and used without further purification.
[5]
transformations. In many of this reports, the amino
[
1a]
[6]
acids
and amine contained rings such as imidazoles ,
[7]
[8]
triazoles and pyridines have been used as ligand to
produce the ionic functions onto the NPs surface and
they are denoted as ionic liquid (IL) functionalized mag-
netic silica NPs.
2.2 | Characterization techniques
FTIR spectra were recorded on a Bomem MB‐Series FT‐IR
spectrophotometer. Transmission electron microscopy
(
TEM) analysis was performed using a ZEISS EM‐900 at
Oxidation of alcohols to corresponding carbonyl com-
pounds (e.g. aldehydes, ketones and acids) is one of the
important organic transformations both for fundamental
an acceleration voltage of 80 kV. Scanning electron
microscopy (SEM) and EDX were performed on a Philips
XL‐300 instrument. The sample was sputtered by gold to
avoid undesirable electron charging. Catalysis products
were analyzed using a Varian 3900 GC by the undecane
internal standard. Thermogravimetric analysis (TGA)
was carried out using an STA 1500 instrument at a heating
rate of 10 °C min in air. X‐ray powder diffraction (XRD)
data were collected on an XD‐3A diffractometer using Cu
Karadiation. The concentration of nickel was estimated
using inductively coupled plasma optical emission spec-
trometer (ICP‐OES) Varian Vista PRO Radial.
[9]
research and industrial manufacturing. The main chal-
lenge in the oxidation of alcohols is selectivity of the
[10]
methods to produce the single product.
In conven-
tional methods, oxidation of alcohols were carried out
using stoichiometric amount of toxic oxidant such as
−
1
[
11]
[12]
potassium dichromate,
manganate,
nitric acid,
potassium per-
[13]
[14]
[15]
sodium hypochlorite
and peroxides.
However, the novel reports were focused on methods
containing of nontoxic oxidant in the presence of recycla-
ble catalyst that are consisted with goals of green chemis-
[16]
try.
Aerobic oxidation is green method for oxidation of
alcohols and other organic substrates by molecular oxy-
gen or air as an oxidant in presence of the transition
2
.3 | Preparation of APTES coated
magnetite NPs (Fe O @SiO –NH )
[17]
[18]
3
4
2
2
metals
reported by different catalyst.
catalytic systems based on NPs was designed aerobic oxi-
or free‐radical initiator
that was abundantly
In this direction, many
[19]
Magnetite (Fe O ) nanoparticles (NPs) were prepared
using the previously reported method
tion) and coated with APTES in 2‐propanol (sol–gel
method). In brief, 0.036 mol of FeCl .6H O and
3
4
[
1a]
(co‐precipita-
[
20]
dation
Au@Polystyrene,
TEMPO,
of
alcohols
such
as
MnO @GO,
2
[21]
magnetic
silica [24]supported‐
3
2
[
22]
[23]
Pd@PMO‐IL
and Au@SiO2.
0.018 mol of FeCl .4H O were dissolved in 20 ml deion-
2 2
Reengineering approach is one of the most efficient
ized water under nitrogen gas with vigorous stirring.
tools to provide the new route for simplifying the promi-
Then, NH (25%) was added into the solution until the
3
[25]
nent organic reactions.
This concept defined as the
pH of the solution reached to 10. Stirring was continued
for 1 h at 60 °C. The color of the bulk solution turned
from orange to black immediately. The magnetite precip-
itate was separated from the solution using a magnet,
washed several times with deionized water and ethanol,
and dried at ambient temperature. Then, the obtained
magnetic NPs powder (300 mg) was dispersed in 2‐
propanol (150 ml) and water (15 ml) by sonication, and
APTES (99%, 120 μl) was added to the mixture. After stir-
ring for 7 h, the suspended substance was separated from
the solution using a magnet and washed three times with
ethanol. The precipitated product (Fe O @SiO –NH )
analysis and redesign of the reaction conditions based
on the changing in the starting materials such as replac-
ing one of the reaction components with two or more
[
26]
simple and readily available materials,
and in situ pro-
[
27]
viding the starting material (tandem process).
In the
last two decades, many types of the reengineering
approaches in the organic transformations were reported
[
28]
based on tandem oxidative or reductive processes.
In continuation of our interest to design the
[8,29]
nanocatalyst and oxidation of alcohols,
herein, we
aimed to produce the new ionic liquid functionalized‐
3
4
2
2
magnatic silica NPs and immobilize the Ni NPs onto their
was dried at room temperature.

HOSSEINZADEH‐KHANMIRI ET AL.
3 of 9
SCHEME 1 Preparation of sulfonated
ionic liquid‐functionalized magnetic silica
supported‐Ni NPs (Ni@SIL‐MS NPs)
2
.4 | Preparation of ionic liquid‐
temperature for 1 h and dried after separation. In order
to ensure that all of sulfonic groups were protonated,
the residue solid was suspended in 5 wt% sulfuric acid
solution for 15 min, separated, washed with water and
dried at ambient temperature. The sulfonated NPs were
functionalized magnetic NPs
The Fe O @SiO –NH NPs (200 mg) were dispersed in
3
4
2
2
2
50 ml round bottom flask containing of benzil (1 mmol),
2‐pyridinecarbaldehyde (1 mmol) and ammonium acetate
dispersed in solution of NiCl (2 mmol) in deionized
2
(4 mmol) under magnetic stirring for 3 h at 90 °C. Then,
water and stirring for 2 h. NaBH (0.2 mmol) was added
4
the reaction mixture was diluted by 20 ml ethanol, func-
tionalized NPs were separated and washed three times
with ethanol. The obtained NPs were dried at 70 °C and
reacted with 3‐chloropropanethiol (3 mmol) in acetoni-
trile (20 ml) at 70 °C for 24 h. After completion the reac-
tion the ionic liquid‐functionalized NPs were collected
with external magnet and washed with ethanol.
to the reaction mixture and continued the stirring for
24 h. The sulfonated ionic liquid‐functionalized magnetic
supported Ni NPs (Ni@SIL‐MN) were separated, washed
and dried the same of previous step. The loading of nickel
−1
was measured to be 0.60 mmol g by inductively coupled
plasma‐optical emission spectrometry (ICP‐OES).
2
.6 | General procedure for selective
2.5 | Preparation of sulfonated ionic
oxidation of primary alcohols to aldehydes
liquid‐functionalized magnetic supported
The catalyst (0.06 g, 3.6 mmol %) was added to the mix-
ture of alcohol (1 mmol) in deionized water and stirred
at 90 °C for 1 hr under air blowing. The completion of
reaction was monitored by tin layer chromatography
Ni NPs
The ionic liquid‐functionalized NPs (200 mg) were stir-
ring in the 33% H O2 solution (32 ml) at ambient
2

4
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HOSSEINZADEH‐KHANMIRI ET AL.
(
TLC). At the end of reaction, the catalyst was separated
anchoring of silica onto the surface of magnetites, while
this band was overlapped with the Fe–O vibration. In
other words, the formation of Fe–O–Si bonds upon silica
coating affected the position of Fe–O bands, and a peak
shift occurred. The Si–O–Si stretching and bending vibra-
by external magnet, the reaction solution was extracted
by CHCl analyzed by GC method.
3
2
.7 | General procedure for tandem
−1
[1a]
tions appeared at 1080 and 463 cm , respectively.
synthesis of arylidienemalononitriles,
bisindolylmethanes and
bishydroxycumarinomethanes
−1
The peaks at 3450, 1120 and 967 cm are signified to
the stretching, asymmetric stretching, and bending of
Si–OH groups (silanol) on the silica surface, respectively.
−
1
Vibrations at 3600–3400, 1637 and 800 cm correspond
to the adsorbed water (H–OH, stretching vibration),
residual intermolecular water (H–OH, bending), and
moisture (H–OH, bending) in the NPs structure. In addi-
The catalyst (0.08 g, 4.8 mmol %) was added to the mix-
ture of alcohol (2 mmol) and second reagent
[
(
malononitril (1 mmol), indoles or 4‐hydroxycumarin
2 mmol)] in deionized water and stirred for 1 hr at
0 °C under air blowing. After completion the reaction
tion, the spectrum of the Fe O @SiO –NH shows peaks
9
3
−1
4
2
2
−
1
at 2847 cm and 2926 cm due to C–H bonds of ali-
as indicated by TLC catalyst was separated, and the prod-
uct was purified by recrystallization at hot ethanol.
phatic chain stretching vibrations, while the two broad
−
1
bands at 1580 and 3403 cm are attributed to the N–H
[30]
stretching and bending vibrations, respectively.
After
2
.8 | Catalyst recovery procedure
functionalization with ionic liquid, new peaks at 2780–
−
1
2920 cm attributed to stretching vibration of CH ali-
After each run of the tandem reactions, the catalyst mag-
netically collected, washed three times with ethanol and
then dried at 80 °C for 2 h. The recovered catalyst was
keep on 110 °C for 1 h before the next reaction run due
to the activation of the catalyst available surface by
removal the volatile and moisture.
phatic of extra propyl chains were appeared with propyl
chain of ATPES and the vibrations of SH bond located
−
1
as a broad peak at 2550–2630 cm . The stretching vibra-
tion of C=C and C=N bonds with unreacted NH and
2
bending absorption of intermolecular water appeared at
−
1 [7]
1
600–1690 cm . The bending pattern of vibration of
−
1
phenyl CH is caused of new peak at 876 cm , and the
−
1
3
| RESULTS AND DISCUSSION
C‐S bond were appeared at 720 cm . After oxidation of
thiolgroups to sulfonate and protonation, the peak of
the SH was removed and the S=O vibrations were
appeared at 1020–1280 that overlapped with Si–O–Si
The Ni@SIL‐MN NPs were synthesized by multi step reac-
tion, initially the magnetite NPs were prepared and coated
with a layer of organosilicate that provided the magnetite
silica NPs with propylamine onto the available surfaces.
These modified NPs were functionalized via a four‐compo-
nent reaction of benzil, aldehyde, ammonium salt and
propylamine group of the NPs to produce substituted
imidazole ring onto the NPs surfaces. The obtained func-
tionalized NPs were reacted 3‐chloropropanethiol and
provided the imidazolium based ionic liquid on the NPs
that terminated by propylthiol chain. The terminal SH
groups were oxidized to form the sulfonated imidazolium
based ionic liquid. The prepared Ni@SIL‐MN NPs were
characterized by means of various techniques.
[
31]
stretching peaks.
The XRD pattern of Fe O @SiO ‐SO H and Ni@SIL‐
3
4
2
3
MN NPs are shown in Figure S2. The appearance of
Fe O peaks at 18.4, 30.2, 35.3, 43.3, 53.7, 57.0 and 63.1
3
4
in both spectra indicates the inverse spinel structure of
Fe O which agrees with the published magnetite pattern
3
4
[
32]
(JCPDS 19–629).
As for the XRD patterns of Ni@SIL‐
MN NPs, a characteristic peaks at 2θ of, 42.6 and 52.7
[33]
are also observed that corresponded to Ni NPs.
The
XRD results confirmed that the magnetite structure were
retained through the modification and functionalization
processes, and Ni NPs were successfully synthesized onto
the surface of functionalized NPs.
The stages of the catalyst preparation were identified
by FTIR spectroscopy. Figure S1 (see supplementary data)
shows the FTIR spectra of the Fe O , Fe O @SiO –NH
The
thermogravimetric
analysis
of
Fe O ,
3 4
Fe O @SiO ‐SO H and Ni@SIL‐MN are shown in Figure
3
4
3
4
2
2,
3
4
2
3
Fe O @SiO ‐SH and Fe O @SiO ‐SO H. The peaks at
S3. The curves show the initial weight losing before
120 °C due to the elimination of moisture and Volatiles.
After modification and functionalization of magnetic
NPs, the new steps of the weight losing at 276 and
383 °C are occurred respect to the decomposing their
organic contents. Comparison the remaining weights of
Fe O4 and Fe O @SiO ‐SO H indicated that the
3
4
2
3
4
2
3
−
1
6
40, 594 and 446 cm are ascribed to the stretching vibra-
−
1
tions of Fe–O bonds, and the absorption peak at 3253 cm
is the OH stretching vibration characteristic peak, indicat-
[
7]
ing the presence of ferric hydroxide in Fe O NPs.
3
4
ATPES‐coated Fe O is expected to produce a correspond-
3
4
−
1
ing peak of Fe–O–Si bonds at 589 cm resulting from the
3
3
4
2
3

HOSSEINZADEH‐KHANMIRI ET AL.
5 of 9
percentage of organic content is 5.4 after functiona-
lization. In the case of Ni@SIL‐MN NPs, the remaining
weight was increased that signified the existence of more
inorganic content corresponding to immobilization of Ni
NPs (0.31 wt %). The percentage of the Ni NPs are in a
good agreement with ICP‐OES data.
and low than 5 nm respect to Fe O and Ni NPs, respec-
tively. Also, the EDX analysis of Ni@SIL‐MN are shown
the all of desired elements (Figure S4 g).
3
4
The specific surface area of the samples was measured
using a BET method with N adsorption–desorption at
2
−196 °C, and the typical results were shown in Figure
The SEM images of modified magnetic silica NPs and
Ni@SIL‐MN NPs are presented in the Figure S4, which
are shown the aggregated semi‐spherical particles with
average diameters of 78–95 nm for modified magnetic sil-
ica. In the case of Ni@SIL‐MN, the particles have a large
diameters of particles by average diameters about 100 nm,
due to the presence of sulfonated ionic liquid dendrimers
onto the surface that supported Ni NPs. These NPs show
the low degree of aggregation between spherical particles.
In addition the TEM images of the final catalyst are con-
firmed the core‐shell structure of the NPs with two types
of the dispersed small particles in their structures. The
average sizes of these particles are measured 10–20 nm
S5. The hysteresis loop appeared in the range of
0.5 < P/P < 1.0 is related to capillary condensation.
o
According to IUPAC classification, these isotherms was
classified in type IV that shown an H1 hysteresis loop.
This is characteristic of the highly ordered mesoporous
material. The BET surface area of Ni@SIL‐MN is
2
−1
312.7 m g and the average pore size is 6.3 nm.
As a second part of this research, the catalytic activity
of the Ni@SIL‐MN NPs in the aerobic oxidation of the
primary alcohols to aldehydes was evaluated. In order
to optimize the reaction conditions, oxidation of benzyl
alcohol was chosen as a model reaction, and the reaction
was carried out in various conditions such as solvent,
a
TABLE 1 Optimization the reaction condition
b
Entry
Gram of catalyst (mol%)
Additive (mol%)
Solvent
T (°C)
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
9
0.04 (2.4)
0.06 (3.6)
0.08 (4.8)
0.04 (2.4)
0.04 (2.4)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
0.06 (3.6)
‐
‐
‐
‐
‐
‐
‐
‐
‐
‐
‐
Water
25
25
25
60
80
80
25
80
90
25
110
25
25
25
25
25
110
140
80
80
80
12
12
12
2
‐
Water
12
water
15
Water
38
Water
2
80
Water
1
92
S.F.
12
2
trace
73
S.F.
S.F.
2
81
10
11
12
13
14
15
16
17
18
19
20
21
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
o‐xylene
Acetonitrile
Water
12
12
12
12
12
12
12
4
‐
40
K
2
2
CO
3
(30)
(50)
trace
trace
trace
trace
trace
78
K
CO
3
Na
2
3
CO (50)
KOH (50)
NaOH (50)
K
K
K
‐
2
2
2
CO
CO
CO
3
3
3
(50)
(50)
(50)
4
81
8
75
c
0.002 (3.6)
12
12
‐
d
0.06
‐
Water
‐
a
b
c
d
benzyl alcohol (1 mmol), catalyst and solvent (5 ml) under air blowing, CG measured yield. Ni NPs as catalyst. Fe
3
O
4
@SiO
2
‐SO
3
H as catalyst.

6
of 9
HOSSEINZADEH‐KHANMIRI ET AL.
a
catalyst and temperature. Initially, deionized water was
used as reaction medium, and the reaction was per-
formed in the presence of various amounts of catalyst at
different temperatures under air blowing (Table 1). No
product was detected in water with 2.4 mol% of catalyst
at ambient temperature. However, when the amount of
the catalyst was increased, yield of reaction was slightly
raised. Furthermore, the model reaction was repeated at
higher temperature conditions, and the reaction yield
was increased to 92% at 80 °C. Subsequently, the solvent
free conditions (S.F.) was studied that provided the good
TABLE 4 Tandem oxidative synthesis of bisindolylmethanes
a
TABLE 2 Aerobic oxidation of primary alcohols
a
alcohol (1 mmol), catalyst (0.06 g, 3.6 mmol%) and water (5 ml) under air
b
blowing at 80 °C, CG measured yield.
a
alcohol (2 mmol), indoles (1 mmol), catalyst (0.08 g, 4.8 mmol%) and water
b
(
5 ml) under air blowing at 80 °C, isolated yield.
a
TABLE 3 Tandem oxidative synthesis of alkylacrylonitriles
yield at 90 °C. As complementary study of reaction opti-
mization, the reaction progress was investigated in vari-
ous organic solvent such as toluene, o‐xylene and
acetonitrile. In the case of toluene, the reaction was failed
to produce the product at ambient temperature and pro-
duced the low yield at reflux condition. According to
[
34]
the same reports for alcohol oxidation,
reaction was
carried out in presence of base and the best result was
provided with 50 mol% of K CO at reflux conditions
2
3
(
78%). Similarly, the good yield such as 81 and 75% pro-
vided in o‐xylene and acetonitrile, respectively. It is prom-
inent to note that the reaction was examined in the
presence of Ni NPs under optimized conditions, and the
reaction not performed. Likely, the reaction was repeated
using same amount of Fe O @SiO ‐SO H that was failed.
3
4
2
3
The results confirmed the synergic effect of the function-
alized silica NPs on the catalytic activity of Ni NPs in aer-
obic oxidation of primary alcohols.
In order to investigate the scope and limitations of
this catalyst in the selective aerobic oxidation of alco-
hols to corresponding aldehydes, a variety of primary
a
alcohol (2 mmol), cyanomethanes (1 mmol), catalyst (0.08 g, 4.8 mmol%)
b
and water (5 ml) under air blowing at 80 °C, isolated yield.

HOSSEINZADEH‐KHANMIRI ET AL.
7 of 9
alcohols were used in the optimized reaction
conditions. All products were obtained in high yields.
The structure of the products are presented in the
Table 2.
In view of the success of above mentioned reactions,
we decided to extend the study to two types of tandem
oxidative reactions for synthesis of alkylacrylonitriles
and bisindolylmethanes that starting from alcohols. The
reaction of malononitrile and benzyl alcohol in the opti-
mized oxidation conditions was chosen as model for reac-
tion for synthesis of alkylacrylonitrile derivatives.
The reaction results showed a good ability of this sys-
tem in the synthesis of benzylidenemalononitrile as
desired product after 1.5 hr with 95% yield. The substrate
scope of the tandem oxidative reaction was investigated.
Two different cyanomethanes such as malononitrile and
ethylcyanoacetate with various primary alcohols were
used under the optimized reaction conditions. The results
were showed in Table 3 that all reactions carried out in
good yields.
According to the good performance of the catalyst
system for the synthesis of alkylacrylonitrile derivatives
FIGURE 1 FTIR spectrum of the
recovered catalyst (a) Recyclability of the
catalyst (b)
TABLE 5 Comparison of the results for the oxidation of benzyl alcohol
Entry
Catalyst
Conditions
Time
Yield
Reference
[
[
[
[
31]
32]
33]
34]
1
2
3
4
5
PhenS*Pd (OAc)
2
Water, NaOAc, air, 100 °C, 30 bar pressure
10 h
1.5 h
6 h
93
97
87
31
92
ARP‐Pd
Water, O
Water, TEMPO, K
Toluene, O , 90 °C
Water, K CO , air, 80 °C
2
, 100 °C
PEG‐PyTa, Cu (OTf)
Ni‐Al hydrotalcite
Ni@SIL‐MN NPs
2
2 3 2
CO , O , 25 °C
2
12 h
1 h
2
3
This work

8
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HOSSEINZADEH‐KHANMIRI ET AL.
ACKNOWLEDGEMENTS
The authors would like to thank Tabriz Branch, Islamic
Azad University for the financial support of this research.
ORCID
Rahim Hosseinzadeh‐Khanmiri
003-4900-1824
http://orcid.org/0000-
0
FIGURE 2 Proposed mechanism
REFERENCES
via tandem oxidative reaction, the tandem oxidative syn-
thesis of bisindolylmethanes was proceeded using the
same process. For this purpose, indole and benzylalcohol
were reacted under oxidation conditions. This reactions
were accomplished less than 2 hr. As shown in the
Table 4, using this methods six derivatives of
bisindolylmethanes were synthesized and characterized
with physical derivatives.
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How to cite this article: Hosseinzadeh‐
Khanmiri R, Kamel Y, Keshvari Z, et al. Synthesis
and characterization of a Ni nanoparticle stabilized
on Ionic liquid‐functionalized magnetic Silica
nanoparticles for tandem oxidative reaction of
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